Editing Michelson–Morley experiment (section)

=== Incorrect alternatives ===
As mentioned above, Michelson initially believed that his experiment would confirm Stokes' theory, according to which the aether was fully dragged in the vicinity of the Earth (see [[Aether drag hypothesis]]). However, complete aether drag contradicts the observed [[aberration of light]] and was contradicted by other experiments as well. In addition, Lorentz showed in 1886 that Stokes's attempt to explain aberration is contradictory.<ref group=A name=Jan /><ref group=A name=Whittaker />

Furthermore, the assumption that the aether is not carried in the vicinity, but only ''within'' matter, was very problematic as shown by the [[Hammar experiment]] (1935). Hammar directed one leg of his interferometer through a heavy metal pipe plugged with lead. If aether were dragged by mass, it was theorized that the mass of the sealed metal pipe would have been enough to cause a visible effect. Once again, no effect was seen, so aether-drag theories are considered to be disproven.

[[Walther Ritz]]'s [[Emission theory (relativity)|emission theory]] (or ballistic theory) was also consistent with the results of the experiment, not requiring aether. The theory postulates that light has always the same velocity in respect to the source.<ref name=norton group=A /> However [[De Sitter double star experiment|de Sitter]] noted that emitter theory predicted several optical effects that were not seen in observations of binary stars in which the light from the two stars could be measured in a [[spectrometer]]. If emission theory were correct, the light from the stars should experience unusual fringe shifting due to the velocity of the stars being added to the speed of the light, but no such effect could be seen. It was later shown by [[J. G. Fox]] that the original de Sitter experiments were flawed due to [[Extinction theorem of Ewald and Oseen|extinction]],<ref name=fox65>{{Citation|last=Fox |first=J. G.|title=Evidence Against Emission Theories|journal=American Journal of Physics|volume=33|issue=1|year=1965|pages=1–17|doi=10.1119/1.1971219|postscript=.|bibcode = 1965AmJPh..33....1F }}</ref> but in 1977 Brecher observed X-rays from binary star systems with similar null results.<ref>{{Cite journal|last=Brecher |first=K.|title=Is the speed of light independent of the velocity of the source|journal=Physical Review Letters|volume=39|year=1977|pages=1051–1054|doi=10.1103/PhysRevLett.39.1051|bibcode=1977PhRvL..39.1051B|issue=17}}</ref> Furthermore, Filippas and Fox (1964) conducted terrestrial [[particle accelerator]] tests specifically designed to address Fox's earlier "extinction" objection, the results being inconsistent with source dependence of the speed of light.<ref name=FilippasFox>{{cite journal|last1=Filippas |first1=T.A. |last2=Fox |first2=J.G.|title=Velocity of Gamma Rays from a Moving Source|journal=Physical Review|year=1964|volume=135|issue=4B|pages=B1071–1075|bibcode = 1964PhRv..135.1071F |doi = 10.1103/PhysRev.135.B1071 }}</ref>